body {
    font: 14px "Lucida Grande", Helvetica, Arial, sans-serif;
}

* {
    padding: 0;
    margin: 0;
}

h1 {
    position: absolute;
    top: 3%;
    left: 50%;
    transform: translate(-50%, 0);
}

input[type='button'] {
    display: block;
    position: absolute;
    top: 7%;
    right: 20%;
    width: 100px;
    height: 30px;
    text-align: center;
}

.box {
    width: 90%;
    height: 85%;
    position: absolute;
    top: 12%;
    left: 50%;
    transform: translate(-50%, 0);
    overflow: hidden;
}

.box table {
    width: 900px;
    margin: 0 auto;
    table-layout : fixed;
}

.box table tr:nth-child(even) {
    background: #b6bfeb;
}

.box table tr th,
.box table tr td {
    height: 36px;
    text-align: center;
}

.box table tr td:nth-child(3n-1) {
    width: 50px;
}
